The following description is provided to assist the understanding of the reader. None of the information provided or references cited is admitted to be prior art.
A fuel cell is an electrochemical unit that converts chemical energy into an electrical current. The electric current is generated through chemical reactions using an input source, i.e., a fuel, that is oxidized in the presence of an electron producing catalyst. The oxidation typically occurs at an anode proximal to an electrolyte medium. The electrons cannot pass through the electrolyte medium, and thus, are shunted through an electrical circuit, which generates an electrical current by the transfer of electrons from an anode to a cathode. The reaction products accordingly form at the cathode.
Fuel cells can operate continuously by maintaining a constant source of chemical reactants. As such, fuel cells are distinct from electrochemical batteries, which produce an electrical current from an internal—thermodynamically closed—system, because fuel cells require reactants from an external source that can be replenished, i.e., thermodynamically “open” systems. Such replenishable systems require an energy source and an oxidizing agent. For example, hydrogen fuel cells use hydrogen as the source and oxygen as an oxidizing agent. These fuel cells may use oxygen and a hydrocarbon, e.g., methane, methanol, ethanol, etc., as the oxidizing agent and the fuel source, respectively, which consequently produces water and carbon dioxide (CO2) as the reaction products.
Microbial fuel cells (MFCs), on the other hand, require a biochemical source of fuel or energy, i.e., from a “biomass,” to facilitate proliferation of electrogenic bacterial cultures. While biomasses can be present in a variety of sources, electrogenic cultures are nevertheless difficult to maintain insofar as such cultures possess disparate metabolic requirements compared to other microbial cultures, i.e., possessing non-electrogenic bacteria. Further complicating MFC operation is that, even when carefully controlled, electrogenic cultures typically fail to maintain surface electrode confluence which imparts decreased performance and efficiency. Accordingly, new MFC devices, methods and systems are needed in industries seeking to remediate source contamination while efficiently generating electricity.